Hello and welcome to android enthusiasts! Please edit your answer to include a source if possible and don't use caps lock in your answers.
– benjaminSep 7 '16 at 13:21

1

Quoting CyanogenMod/android_frameworks_opt_net_ims: At the moment, this only supports VoLTE calls which is compliant to GSMA IR.92 specification. So there is at least some VoLTE support. Also, this Changelog for CM13 mentions add volte feature system property and api's as well as set volte feature enable in ImsManager when Volte service is updated bb7de1a telephony. Side-marks point to a possible dependency on hardware/service.
– Izzy♦Sep 7 '16 at 14:58